The Friendly Atheist, Hemant Mehta, brings this chart to our attention. He would like to see Atheists as a group. One commenter makes an important point after reading what other commenters wrote:

Some people here seem to be confusing this chart with percentage of the population rather than percentage of evolution acceptors in each category. Keep in mind that the tall bars on the left represent very small percentages of the U.S. population. If atheists were separated out of the “unaffiliated” category, even though they are a small percent of the population, their bar would probably be the tallest.